Technical Field
The invention relates generally to marine seismic prospecting and in particular to sensor arrangements for gathering seismic data.
Description of the Related Art
In towed marine seismic exploration, a hydrophone array is towed behind a marine vessel near the sea surface. The hydrophones are mounted in multiple sensor cables commonly referred to as streamers. The streamers serve as platforms for the hydrophones. A seismic sound source, also towed near the sea surface, periodically emits acoustic energy. The acoustic energy of interest travels downward through the sea, reflects off underlying structures or subsea strata, and returns upward through the sea to the hydrophone array. Reflected seismic energy arrives at towed-array receive points. The hydrophone array contains many such receive points, and their records contain the upward traveling seismic acoustic wavelet from the seabed at each of the receive points. The hydrophone recordings are later processed into seismic images of the underlying structures.
Noise is a major consideration in towed streamer operations. Noise sources include swell noise and wave noise from the sea surface. Towing the streamer through the water also causes noise. Some of this noise propagates through the streamer and some through the water column itself. The presence of such noise can adversely affect the accuracy of the sub-surface image. Accordingly, what is needed is an improved sensor system for recording seismic data, wherein the sensor system captures the seismic data but substantially rejects noise.